This work will involve investigations into the mechanism whereby insulin stimulates the sodium pump and membrane-bound Na-K ions ATPase. The principal approach will involve kinetic studies on intact muscle cells coupled with studies of the Na-K ions ATPase isolated from muscle as well as from brain. The possibility that the sodium pump can also transport H ions will be investigated as will the hypothesis that insulin causes the pump to efflux H ions and as a result increase intracellular pH(pHi). The flux experiments will be conducted mostly on frog skeletal muscles with the muscle from one leg serving as a paired control for the other. Many of the enzyme experiments will be conducted on Na-K ions ATPase isolated from rat brain. The first objective will be to test the hypothesis that insulin stimulation of the sodium pump is due to an increase in the association constant for Na ions of the carrier sites facing the inner side of the membrane (Moore, 1973). A second, and closely related objective, will be to determine if insulin increases pHi. Intravellular pH will be determined by the use of DMO-14C (14C 5,5-dimethyl 1-2,4-oxazolidinedione) as well as by pH sensitive glass microelectrodes. Any advances in understanding which may come from this work will very likely increase our insight into the molecular and cellular action of insulin as well as into the reason for frequent failure of long-term diabetic therapy. BIBLIOGRAPHIC REFERENCES: K. Schin & R.D. Moore. 1977. Cation concentration in the haemolymph of a fly, Chironomus thummi, during development. J. Insect Physiol., in press. S.Y. Chan & R.D. Moore. 1977. Effect of insulin upon Na efflux as a function of intracellular Na. Biophysical J. 17:154a.